Sand-blasting machine



Dec. 10, 1929.

H. A. MULVANY ET AL.

SAND BLASTING MACHINE Filed May 17, 1923 2 Sheets-Sheet l [NT/EIVTOR HARRYA.MUL WINY JEMERY 1E KENNEDY ATY'UfP/VEKS Dec. 10, 1929. H. A. MULVANY ET AL SAND BLASTING MACHINE File d May 17, 1923 2 Sheets-Sheet 2 [NWNZTOR RR YA .NUL VAN) 7 HARRXEKE'NA/EDY 5y 22m 4d :3 ATTORNEKQ mmtedi ii 10, 1929 UNITED STATES PATENT OFFICE HARRY A. MUL'VANY AND HARRY E. KENNEDY, F BERKELEY, CALIFORNIA SAND-BLASTING MACHINE Application filed May 17, 1923. Serial No. 639,513.

This invention relates to a sand blasting machine, and particularly to a machine for sand blasting or dryclaning eggs, but We wish it understood that it is applicable, as

a will later be described, to other articles, food products, etc.

The object of the present invention is to provide a machine whereby eggs in large quantities may be cleaned by subjecting the same to the abrasive action of a sand blast. We accomplish this object by providing a foraminous, horizontally disposed carrier; by imparting movement to the carrier and by imparting a rotary movement to the eggs or articles supported by the carrier, and further by directing a sand blast vertically and downwardly through the foraminous carrier during movement of the same and during rotation of the eggs or articles to be cleaned.

One form which our invention may assume is examplified in the following description and illustrated in the accompanying drawings, in which- Fig. 1 is a side elevation of the machine partially in section.

Fig. 2 is an enlarged cross-section of the rollers carried by the endless conveyors.

Fig. 3 is an enlarged cross-section on line 33, Fig. 1.

Fig. 4 is a central, vertical cross-section taken on line 4-4, Fig. 1.

Fig. 5 is an enlarged sectional detail view showing one of the nozzles.

Fig. 6 is adiagrammatic View showing the manner in which the eggs are rotated while subjected to the sand blast.

Referring to the drawings in detail, an particularly to Figs. 1 and 2, A indicates a housing in which is formed a central passage or a tunnel B. Forming a cover or top for the passage is a plate 2, and attached to the lower side of said plate are a plurality of blasting nozzles generally indicated at C. Disposed above the cover plate 2 is a secend plate 3, and formed between said plates is a chamber 4 to which air is admitted from a blower or the like through means of a pipe 5. The plate 3 forms the bottom portion of a sand hopper 6 to which sand is continuously delivered by means of a pair of endless chain bucket conveyors, such as indicated at 7 and 8; "these conveyors being carried by upper and lower sets of sprocket gears carried by cross-shafts 9 and 10 extending through the housing and journalled therein, and which may be driven in any suitable manner. The lower portion of the housing forms a receiving hopper for the sand as indicated at 11, but the sand received is continuously elevated and returned to the hopper 6 due to the continuous movement of the conveyors and the buckets carried thereby. Formed above the sand hopper is a separating or settling chamber 12, and disposed in said chamber is a separator of the cyclone type which is generally indicated at l) and which will hereinafter be referred to.

The blasting nozzles generally indicated at C are perhaps best illustrated in Fig. 5. Each nozzle is provided with a central passage 13 and a pair of laterally extending communicating air passages 14:; the three passages being cored, drilled or otherwise formed. The upper ends of the passages 14 are internally threaded to receive a pair of pipes or tubes 15. These pipes pass through the plates 2 and 3 and the air chamber 4, and their upper ends are threaded to receive securing nuts 16. These nuts do not only secure the pipes 15 against endwise movement, but they also secure the nozzles in position with relation to the lower plate 2. This can readily be seen as the pipes 15 are screwed into the passages 14 and as such serve as tie rods to pull the nozzle tightly against the bottom plate 2 and to secure it with relation thereto; a gasket 17 being interposed to form an air-tight joint, and gaskets being similarly interposed between the nuts 16 and the plate 3 to make air-tight connections at these points. The upper ends of the tubes 15 are open and they communicate with the sand hopper 6. Sand is therefore permitted to drop by gravity through the tubes and as they communicate with the passages 14 and these in turn with the central passage 13, it can readily be seen that the sand entering the nozzle through the tubes 15 is finally delivered to the central passage 13, and that the sand is here ejected with considerable force as the air entering the chamber 4 under fairly high velocity discharges downwardly through the central passage 13. The sand and air are thus thoroughly mixed and as such are directed downwardly with considerable force against the articles to be cleansed.

E indicates the feeding end of the machine and F the discharge end of the machine. In this instance we will suppose that we are cleaning eggs. If that is the case, the eggs are deposited in any suitable manner on a conveyor generally indicated at G, at the point indicated at E. This conveyor passes through the central passage or tunnel B and thus carries the articles to be cleansed under the blasting nozzles, thus subjecting them to the abrasive and cleaning action of the sand and finally discharging the same at the point indicated at F, where they are removed in any suitable manner. There are two conveyors employed, that indicated at G and that indicated at H. These conveyors are practically identical in construction and-function and will hereinafter be referred to.

The conveyor E consists of a pair of parallel endless linked chains, such as indicated at 20 and 21. (See Fig. 2.) These chains are carried by sprocket gears such as indicated at 22, 23, 24 and 25, and-the gears are in turn supported on cross-shafts suitably journalled in a frame generally indicated at 26. The second conveyor, indicated at H, also con sists of a pair of endless linked chains, such as indicated at 27 and 28, (see Fig. 2), said chains being supported by pairs of sprocket "gears such as indicated at 29, 30, 31 and 32; said sprocket gears being carried by'crossshafts such as shown in Fig. 1, which are suitabl journalled in the frame 26. The conveyor (g is driven through a chain 35 and cooperating gears disposed at the opposite end of the frame. The detail construction of both conveyors is of considerable importance as these conveyors are continuously subjected to the abrasive and cuttin action of the sand and as such must be carefully protected and alsotaken care of as far as lubrication is con-- cerned. By referring to Figs. 1 and 2, it will be noted that the chains 20 and 21 are connected by cross-rods 40; these rods forming a pivotal connection between the respective links and also a support for intermediate rollers disposed between the chains; these rollers consisting of an inner metal tube 41 and an exterior covering tube constructed of rubher as indicated at 42. Each tube must free- 1 rotate on its rod 20 and means must, therefi ire, be provided for permitting free rotation. In actual practice we first provided a stufiing box ateach end of the tube and filled the interior with grease, but we found that sand and grit would enter and that both the tubes andthe rods would rapidly wear and cut away. This objection has, however, been finally overcome by merely inserting a piece of helical spring wire in each end of the tube 41, as indicated at 42 and 43. One wire is wound in one direction and the other wire is wound in the opposite direction. Each wire is screwed or pressed into its end of the tube, but is freely rotatable about the rod 20. The helical springs therefore form a bearing in each end of each roller and as they furthermore rotate with the rollers, it is obvious that they will have an auger action which will tend to automatically eject any sand or grit which may enter. In actual experience we have found that the spring bearings thus formed require no lubrication, and that their life is practically unlimited as no sand or grit will remain therein due to the screwing or auger action produced by rotation of the springs.

Each roller in the conveyor G is identically constructed, there being one roller disposed between each set of links. These ro1lers form a support for the eggs to be cleansed and as the spacing between the chains 20 and 21 is fairly great and the rollers proportionately long, it is obvious that a considerable number of eggs may be laid in row formation between each set of rollers. The second conveyor indicated at H is, practically speaking, identical in construction to that indicated at G, that is, the chains 27 and 28 are connected by rods 40 which are enclosed by tubes 41 and exterior rubber tubes 42. The spring bearings are similarly provided or disposed at each end of each tube to exclude sand and grit. The only difference in construction is the provision of a rubber-tired Wheel at each end, as indicated at 45. These wheels engage track members 46 which consist of I-beams extending from the point indicated at 47 to the point indicated at 48, in Fig. 1. These I-beams form a track or support for the rollers and the rubber-covered wheels carried thereby, and these wheels in turn form a support for the upper r11bbercovered rollers indicated at 42. The wheels 45 furthermore serve the function of imparting a rotary movement to the upper rollers 42 and they are thus continuously rotated while advancing with the chains. (Fig. 6 diagrammatically illustrates the rotary movement imparted. The lower circles indicate the rubber-tired wheels 45, and the straight line indicates the track 46. 42 indicates the upper set of rollers, and 50 indicates the egg to be cleaned.)

If the conveyors G and H are travelling in the direction of arrow (1, the wheels 45 will rotate in the direction indicated; rollers 42 will rotate in the opposite direction, as indicated, and the egg 50 will rotate in the same direction as the wheels 45. In other words, rotary movement will be imparted to the eggs in the direction of travel. This is one of the important features of the present invention as it causes greater exposure of the exterior egg-shell surface to the action: of the sand menses blast than could otherwise be secured. To clearly explain this feature we will assume that a single line of sand grains is being vertically projected against the egg and in a vertical downward direction, and that the egg is lying stationary on the conveyor as it passes under this single line of projected grains of sand. If this is the case, a mark encircling one-half of the egg will be produced by the abrasive actionof the single line of projected grains of sand. l/Vewill now suppose that the eggs are supported directly on the wheels or rollers 45 and that they rotate in the direction of the rollers indicated at 42; that is, in a direction opposite to that to which they are traveling. in that case, we will find that, if the peripheral turning speed of the egg is equal to the forward movement or speed of the conveyor, a single dot will be formed on the egg by the abrasive action of the single line of grains of sand.

From the foregoing it is obvious that practical results could not be produced if the eggs were permitted to remain stationary on the conveyor and that poor results would be produced if the eggs were rotated in a reverse direction to the line of travel. It is for the above reasons that the eggs are rotated in the same direction as that in which they travel, as illustrated inFig. 6, as it has been found that it is possible to obtain, practically speaking, a complete revolution of each egg as it passes each nozzle and as several nozzles are employed, it is obvious that the eggs will be rotated several revolutions about their longitudinal axis and that the entire surface thereof will be again and again subjected to the abrasive action of the sand and thoroughly cleaned before being discharged.

The conveyors G and H in reality form the bottom portion of the central passage or tun-- nel B, which may be likened unto a cont nuously traveling floor, having longitudinal spaces or openings formed therein, the spaces being partially tilled with eggs to be cleaned. The air and sand projected downwardly against the eggs and the rollers 42 pass through the openings formed between the rollers and impinge against an inclined bottom plate disposed below the conveyors. The sand passes down this plate and discharges into the lower hopper 11, whilethe air passes upwardly to the chamber 12 and finally passes out through the cyclone separator indicated at l).

The cyclone separator consists of a coneshaped shell such as illustrated at 62, in Figs. 1, 3 and 4. The upper portion of the shell is providedwith two tangentially disposed inlet openings 63 through whlch the air enters in the direction of arrows b. Disposed centrally within the casing 62 is a second cylindrical casing 64. This casing is provided with a series of tangentially disposed inlet openings 65 which are reversed with relation to the openings 63. The inner cylinder 64 is connected with the suction side of a blower not here shown through means of a pipe 66 and the air is, therefore, drawn through the cyclone separator at a considerable velocity; that is, the air enters the housing A through the spaces formed between the rollers of the conveyors. G and H. under pressure and high velocity, as indicated by the arrow 6. (See Fig. 4.) It here strikes the inclined plate 60 and it is then deflected upwardly as indicated by arrow (Z. It then enters the outer casing 62 through the tangential openings 63 and finally discharges or enters the suction pipe 66 by entering the inner cylinder through the reversed tangential openings 65. The major portion of the sand, at least the heavy portion thereof, is separated from the air the moment the air strikes the lower plate 60. The lighter material is further separated from the air the moment it starts upwardly in the direction of arrow 0?. Still lighter particles are carried up with the air to the-cyclone separator D, but they are thrown out the moment the air reverses itself within the cyclone separator as indicated by arrows 6, that is, air entering in the direction of arrow 6 reverses itself to enter the openings 65, and itis found that during the reversal of the air that the lighter particles are thrown out against the inside surface of the casing 62 and they here drop vby gravity into the lower cone-shaped end (see Figs. 1 and 4) and are finally returned to the hopper 6 through means of a spout 66. The finer dust and like material is, however, carried away with the air and the sand is thus maintained in a clean condition and as such may be used over and over again and it is for this reason that the continuously operating elevators 7 and 8 are employed.

From the foregoing it can be seen that the machine is continuous in operation as the eggs delivered on one end of the conveyor are automatically advanced and simultaneously rotated in the direction of their travel. They pass in under the sand blasting nozzle while the forward and rotary movement is transmitted to the same and they are thus thor oughly cleansed by the abrasive action of the sand, and they are finally removed at the opposite end of the conveyor. The sand is used over and over again and it is continuously cleaned as the lighter materials and refuse are carried away with the air, while the heavier sand is returned to the feeding hopper again and again. Enormous quantities of eggs can be handled in this manner and no detrimental effect is produced as the natural seal provided by nature remains intact as far as the pores of the eg -shell are concerned.

It is well recognized by those familiar with the poultry business, that eggs, which have been previously washed, are subject to amuch more rapid rate of deterioration than those left in their natural condition. This is due to the fact that nature provides a natural seal which is dissolved and removed during the washing -operation; that is a freshly laid egg is found to be lightly coated with a mucous substance which acts to restrain evaporation and at the same time prevents ingress of bacteria from external sources. This mucous substance is readily soluble in Water and as such is removed when the eggs are subjected to moisture or any wet cleaning operation. The washing of an egg, therefore, produces two harmful results first, that of dissolving and removing the mucous seal, thereby permitting evaporation and ingress of bacteria from external sources, and secondly, that of filling the pores of the shell with a media which readily transmits bacteria. In view of these facts it is obvious that it is exceedingly desirable to cleanse the shell of an egg without removing the natural seal. This is accomplished by the sand blasting operation disclosed in this application;'

that is, all stains and a portion of the mucous substance are removed by the abrasive action of the sand but that portion of'the mucous substance which fills the pores of the shell is not removed and. the seal of the egg is thereby not affected, nor are the keeping qualities of the eggs in any way lessened.

The machine is not only useful for cleaning fresh eggs, but it is also useful when preparing'storage eggs for the market. A great proportion of the storage eggs handled today are coated with a colorless, odorless, tasteless mineral oil. This oil serves as a seal and while it is effective for the purpose sought, it imparts and undesirable color and appearance to the eggs. We have found that oiled eggs when passed through the sand blast are materially improved in appearance as the abraslve action of the sand removes the exteriori oil coating, thus causing the eggs to assume their natural white color. The sand blast furthermore imparts a dull. white finish which is so similar to the natural appearance of a freshly laid egg that the difference is diflicult to detect. The appearance of storage eggs is thus materially improved before they are placed on the market and their keeping qualities are not lessened. The machine is, therefore, not only useful for the handling of freshly laid eggs, but is also useful for preparing storage eggs for the market. We also wish it understood that other articles may be efiiciently handled by this machine and that its use is not limited to the handling of eggs alone.

Having thus described our invention, what we claim and desire to secure by Letters Patent is 1. In a machine of the character described, a conveyor, a plurality of interspaced rollers in said conveyor, said rollers forming a support for articles to be cleansed, means forimparting a longitudinal movement to the conveyor and the rollers carried thereby, and means for rotating the rollers in a direction opposite to the travel of the conveyor, so as to impart a rotary movement to the articles supported thereby in the same direction as the travel of the conveyor.

2. In a machine of the character described an endless conveyor comprising a pair of interspaced chains, rods connecting the links of the respective chains, a tube rotatably mounted on each rod, a resilient covering on each tube, and a helical-shaped bearing member in each end of the tube and supporting the tube with relation to its rod.

3. In a machine of the character described, an endless conveyor comprising a pair of interspaced chains, rods connecting the links of the respective chains and forming a pivotal connection between the respective links, a tube rotatably mounted on each rod, a resilient covering on each tube, and a helical spring secured in each end of each tube, said springs forming a bearing member for each end of each tube and being rotatable with the tubes about the rods, and said sprlngs being wound in opposite directions to produce an angering action whereby entering abrasive material is automatically ejected.

4. In a machine of the character described, an endless conveyor comprising a pair of interspaced chains connected by interspaced rods extending crosswise between the chains, a rubber covered tube journaled on each rod, and a helical-shaped bearing member in each end of each tube.

5. In a machine ofthe charater described, a conveyor, a plurality of interspaced rollers on said conveyor, said rollers forming a support for articles to be cleaned, means for imparting a longitudinal movement to the conveyor, a second eonveyor driven in unison with the first named conveyor and disposed below said first named conveyor, rollers on the second conveyor engaging the rollers on the first named conveyor, and means whereby all the rollers are rotated dur ing movement of the conveyor.

6. In a machine of the character described, a conveyor, a plurality of interspaced rollers on said conveyor, said rollers forming a support for articles to be cleaned, means for imparting a longitudinal movement to the conveyor, a second conveyor driven in unison with the first named conveyor and dis posed below said first named conveyor, rollers on the second conveyor engaging the rollers on the first named conveyor, means whereby all the rollers are rotated during movement of the conveyor, and a track member engaging the rollers on the second named conveyor to rotate the rollers on the second conveyor, and the rollers on the second conveyor, by engaging with the rollers onthe first named conveyor, rotating said rollers and thearticles supported thereby.

7. In a machine of the character described an endless conveyor comprising a pair of interspaced chains, cross rods connecting the chains, a tube rotatably mounted on each rod, and a helically shaped bearing member in each end of the tube and supporting the tube with relation to its rod.

8. In a machine of the character described, an endless conveyor, rollers on the conveyor adapted to support articles to be cleansed;

means for imparting longitudinal movement to the conveyor; and means for rotating the rollers during such longitudinal movement of the conveyor so that the article supported thereby will rotate in the direction of travel of the conveyor.

HARRY A. MULVANY.

HARRY E. KENNEDY. 

